OneBox results at the top of a search results page are often helpful for me (Froogle links, for instance). OneBox results at the bottom are mostly worthless since I usually don't make it to the bottom of the page anyway. The best place for them would be the right side, but of course that would cut into the ad space. :)

I like having the OneBox results on the top, but it would also be nice if they were moved to the side as Jack recommended. Then they would be able to provide more of them from different locations without cluttering up the screen.